Add `_` to some term constants for consistency.

Terms changed:
`CONCATMAP`
`ORDERBY`
`TYPEOF`
`FUNCALL`
`FOREACH`
`GEOJSON`
`TO_GEOJSON`
Revert change to `GEOJSON` terms.
Reverse method aliases in `func.rb` to maintain old methods.
Revert change to `FUNCALL` term.
Fix race condition in mailbox destruction by making mailbox_t destructor block until all callbacks have finished. Mailbox callbacks now take an interruptor signal that is pulsed when the mailbox_t is destroyed.
Catch interrupted_exc_t thrown by mailbox callbacks.
Add clarifying comment.
Catch exception by const reference
Merge branch 'tim_mailbox_destructor_race' into next
stash
encode web assets into C++
Got static web assets to work
python 3 compatible weba ssets script
Added web_assets.hpp
Fix web assets dependencies in makefile
use map::find instead of map::at
Use std::string for static_web_assets
Add missing dependency on web_assets.o to rethinkdb-unittest
Merge branch atnnn/web into next

Review 2203 by @tryneus
Closes #1093
Change the shebang from python3 to python